Liquid phase catalytic hydrocarbon hydroconversion with polyaromatic additive

Abstract

The invention involves the liquid phase hydroconversion of hydrocarbon charges containing heavy fractions, and more particularly their deep conversion, in which the charge is contacted with a dispersed catalyst in the presence of a polyaromatic additive. The catalyst is a sulfide of a hydrogenating metal (such as molybdenum, nickel or cobalt) generated in situ from a precursor. The additive has at least three aromatic cycles, has a boiling point exceeding 300 DEG C., and is added at a rate of 5 to 60% by weight based on the charge. Synergism between the catalyst and the additive makes it possible to reduce the catalyst quantity and/or improve the conversion and quality of the products.

We claim: 
     
       1. A process for the liquid phase hydroconversion to lighter hydrocarbons of a hydrocarbon charge containing heavy fractions having a boiling point exceeding 370° C., said process comprising contacting the charge with 50 to 5000 ppm, based on the charge, of a dispersed catalyst comprising at least one hydrogenating metal sulfide generated in the charge from a precursor, and adding at a rate of 5 to 60% by weight based on the charge at least one non-hydrogen donating polyaromatic additive having a boiling point between 300° and 550° C. and having at least three aromatic rings and maintaining the pressure above 3.5 MPa and the temperature at least 400° C. for a time sufficient to convert at least 50% by weight of the heavy fractions to lighter hydrocarbons. 
     
     
       2. A process according to claim 1, wherein the metal is at least one metal of group IV B, V B, VI B, VII B and VIII. 
     
     
       3. A process according to claim 1, wherein the metal is molybdenum, nickel or cobalt. 
     
     
       4. A process according to claim 1, wherein the catalyst comprises at least two metals. 
     
     
       5. A process according to claim 1, wherein the additive is pyrene, fluoroanthene, anthracene, benzanthracene, dibenzanthracene, perylene, coronene or benzopyrene, each optionally substituted by lower alkyl, or a petroleum fraction having a boiling point between 300° and 550° C. 
     
     
       6. A process according to claim 1, wherein the additive is a liquid phase slurry resulting from catalytic cracking and which has been decanted. 
     
     
       7. A process according to claim 1, in which at least 70% of the heavy fractions with a boiling point above 500° C. are converted into fractions with a boiling point below 500° C., wherein the temperature is equal to or above 430° C. and the pressure is at least 5 MPa. 
     
     
       8. A process according to claim 1, wherein the temperature is between 430° and 450° C. 
     
     
       9. A process according to claim 1, wherein the pressure is between 10 and 15 MPa. 
     
     
       10. A process according to claim 1, wherein the catalyst comprises nickel and molybdenum. 
     
     
       11. A process according to claim 1, wherein the catalyst comprises cobalt and molybdenum. 
     
     
       12. A process according to claim 1, wherein the additive has at least four aromatic rings. 
     
     
       13. A process according to claim 1, wherein the additive is pyrene, fluoroanthene, anthracene, benzanthracene, dibenzanthracene, perylene, coronene, or benzopyrene, each optionally substituted by lower alkyl.